Add 84/28 and 72/21
1st number: 3 0/28, 2nd number: 3 9/21
84/28 + 72/21 is 45/7.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 28 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 28 × 3 = 84,
84/28 = 84 × 3/28 × 3 = 252/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
72/21 = 72 × 4/21 × 4 = 288/84 - Add the two like fractions:
252/84 + 288/84 = 252 + 288/84 = 540/84 - 540/84 simplified gives 45/7
- So, 84/28 + 72/21 = 45/7
In mixed form: 63/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/56+72/21 84/28+72/42 84/28+72/63